Impacts of feeding a flax-seed based feed supplement on production and health of mid through late lactation multiparous Holstein cows on a commercial dairy farm

Abstract

Research in the past 50 years has shown that the general health of dairy cows (i.e., immunity and uterine health) can be improved by higher post-ruminal delivery and absorption of poly unsaturated fatty acids (PUFA), especially omega-3 (n-3) PUFA. Since flaxseed contains high concentrations of n-3 PUFA, our objective was to evaluate effects of feeding flaxseed-based ‘LinPRO-R’ (LinPro), created using dry extrusion, mainly in substitution for cracked Pima cottonseed on production and health of mid-to-late lactation multiparous Holstein cows. Three pens of ∼365 multiparous mid-to-late lactation cows were fed diets formulated to contain 0 g/kg (NoLin), 25 g/kg (LoLin) or 50 g/kg (HiLin) dry matter (DM) of LinPro in a design that rotated cows and diets among pens monthly. Individual body condition (BCS) was scored, and milk yields recorded monthly for four months after assignment to treatment at 154.8 ± 0.10 days in milk (DIM). While ruminal microbial crude protein outflow, estimated using a urine allantoin-based method, was lower (quadratic P < 0.05), and whole tract apparent digestibility of neutral detergent fiber tended (linear P < 0.10) to be higher, with LinPro feeding, DM intake was unaffected. Milk yield and milk components had treatment*DIM interactions (P < 0.05) which indicated biologically small differences in responses to the three diets as DIM increased. Rapid and substantial BCS losses (quadratic P < 0.05) for the LoLin group in the 1st ∼30 days of LinPro feeding was regained in the next 50 days. The lower proportion of cows culled (i.e., removed from the study) for mastitis in both LinPro fed groups (quadratic P < 0.05) suggests improved health of cows fed LinPro. Feeding LinPro at both levels transferred dietary n-3 PUFA into milk (linear P < 0.05), with marked decreases in the n-6 to n-3 FA ratio, thereby improving the healthfulness of the milk fat to its human consumers. Feeding flaxseed as LinPro at 26.7 g/kg of diet DM, but not at 52.4 g/kg, had net benefits in mid-to-late lactation cows, due to similar DM intake and milk production, improved general animal health (i.e., reduced milk somatic cell counts and culling for mastitis), increased milk fat and protein levels, and a higher nutritional value of the milk to its human consumers as suggested by research of health impacts of dairy products in human diets.